PCA9549 Ver la hoja de datos (PDF) - NXP Semiconductors.

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Fabricante

PCA9549

Octal bus switch with individually I2C-bus controlled enables

NXP Semiconductors. 

NXP Semiconductors

PCA9549

Octal bus switch with individually I2C-bus controlled enables

5.0

Vo(sw)

(V)

4.0

3.0

2.0

002aaa964

(1)

(2)

(3)

1.0

2.0 2.5 3.0 3.5 4.0 4.5 5.0 5.5

VDD (V)

(1) maximum.

(2) typical.

(3) minimum.

Fig 7. Vo(sw) voltage versus VDD

Figure 7 shows the voltage characteristics of the pass gate transistors (note that the

PCA9549 is only tested at the points specified in Section 9 “Static characteristics”). In

order for the PCA9549 to act as a voltage translator, the Vo(sw) voltage should be equal to,

or lower than the lowest bus voltage. For example, if the main bus was running at 5 V, and

the downstream buses were 3.3 V and 2.7 V, then Vo(sw) should be equal to or below 2.7 V

to effectively clamp the downstream bus voltages. Looking at Figure 7, we see that Vo(sw)

(maximum) will be at 2.7 V when the PCA9549 supply voltage is 3.5 V or lower so the

PCA9549 supply voltage could be set to 3.3 V. Pull-up resistors can then be used to bring

the bus voltages to their appropriate levels (see Figure 16).

PCA9549_2

Product data sheet

Rev. 02 — 13 July 2009

© NXP B.V. 2009. All rights reserved.

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